Furnace for roasting sulphurous ores



Feb. 18, 1936. w. MUELLER 2,031,122

FURNACE FOR ROASTING SULPHUROUS GREYS Filed 001;. 13, 1953 Patented Feb. 18, 1936 UNITED STATES FURNACE FOR mgnsETNG SULPHUROUS Wilhelm Mueller, Gleiwitz, Germany Application October 13, 1933, Serial No. 693.433

Germany October 18, 1932 Claims. (01. 263-26) The invention relates to roasting furnaces, for roasting of zinc blendes or other sulphurous ores, pyrites and the like, and consists in that the height of the hearths or roasting chambers 5 is strictly limited to the lowest measure and in that the hearths consist of plates of masonry or of metal plates adjustable in vertical direction partly stationary and partly rotatable. These hearths or-plates have radial grooves in or on m the underside, in which the rabble arms with exchangeable rabbler teeth designed to convey the ore forward and downward in the' individual hearths are inserted, and that further the necessary cooling of the rabble arms in the stationary hearths is effected from the outer side by a compressed air conduit, whereas the rabble arms of the rotary hearths are connected to a central cylindrical hollow shaft, through which the cool ing air is supplied under pressure to the individual rabble arms and discharged from them.

In the commonly used mechanical roasting furnaces, such asHerreshofl, Wedge and others, the stirring or rabble arms with the stirring rakes fixed thereon are arranged unsupported on a middle drivingshaft. or the rabblers consist of refractory blocks as in the Spirlet furnaces, which are built into the masonry of the hearths. It has further been proposed to hook the rabblers into hooks or metal'ribs built in the masonry. v

This invention has for its object to eliminate the inconveniences connected with the furnaces of known type in order to attain a more rapid and uniform roasting of the ores to the lowest percentage of sulphur in the finished ores.

An embodimentof the invention is illustrated by way of example in the accompanying drawing in which: I

Fig. 1 shows a roasting furnace in vertical section. I

1 Fig. 2 shows a part of the hearths or roasting chambers'with rabble arms and rabbler teeth in top plan view;

Figs. 3, 3a and 4 show part cross sections through the stage hearths with the rabble arms hearths rotary hearths 2. The rotary hearths 2 are all together rotated from the outer side from an electric motor 5a through the intermediary of a driving shaft 5, pinions l on said shaft and teeth on the circumference of the hearths. The

hearths of. the roasting chambers consist as usual of refractory vaults or plates of masonry clamped on the outer edge in strong iron rings; the vaults may be made of heat resisting thin refractory metal plates in order to reduce the weight and to facilitate the admission of the heat to'and through the ore to be roasted in the next higher roasting chambers. The individual hearth plates I and 2 are either fixed by means of screws on brackets is on lateral supporting columns S or mounted on running rollers R. The roasting chambers are tightly closed annularly on the outer side with refractory sheet metal plates and have packing grooves for the ore. Inspection holes and doors for the introduction of cleaning implements being also pro- 15 vided. 1

According to the invention the hearth plates have radial grooves 9 on the underside and the rabble arms 6 have suitably shaped heads 8 or for metal plates suitably shaped heads 8a, by means of which they engage into the corresponding radial groove of the hearths I and 2 so that they can be inserted or removed from the outer side of the furnace. Two or four stirring arms may be provided for every hearth plate and two or three or if desired more rotatable hearths may be provided, whereas the other hearths between these rotatable hearths are stationary.

For cooling, the rabble arms 6 of the stationary hearths I are connected with the outer conduits l2 and I3, for the supply of cooling air and the discharge of the hot air from the rabble arms, whereas the rabble arms 6 of the rotating hearths 2 are connected. with a double walled shaft III arranged in the centre of the furnace rotating with the hearths and from which the supply of cooling air to and the discharge of the heated cooling air from the rabble arms 6 of the rotating hearths 2' is effected. The air for cooling the rabble arms 6 is forced by means of a pressure fan through the main conduit II partly into the central hollow shaft III and the rabble arms of the rotating hearths 2, and partly through the conduits I2 and I3 from the outer side through the rabble arms of the stationary hearths I, from which the heated cooling air is discharged through similar return conduits. The air cools the rabble arms and the rabbler teeth or'frabblers I fixed on these rabble arms in thatthe air flows and circulates through the one of the tubes 50 6a in the arms in forward direction and-through the other tube 6a in known manner in backward direction, being heated during this time and then admitted into the one or the other roasting chamber from the outer or inner side for as- 55 sisting the roasting process. The heated cooling air is partly conducted at ll to the step grate furnace of the gas producer ll.

During the working of the furnace, the zinc ore, pyrites or the like to be roasted in the furnaceisfedinquantitiesorata-speedadapted to be regulated from the charging hopper Ii through a conveyor worm on to a distributing plate having strippers and thence into the first hearth or roasting chamber, where it is conveyed by means of the rabblers I alternately towards the outer-pr inner side and to the apertures 2| in the individual hearths, throug which it drops. The sulphur contained in the on being separated by roasting during the travelling through the roasting chambers. The lowermost hearth I6 is heated additionally, if necessary, by means of a small producer furnace II with. flues II which heat the lowermost bottom plate of the roasting chamber It with the ores thereon so that the last remainders of sulphur are thus driven out. The ore completely freed from sulphur by roasting drops below into the collecting bunker l9 arranged in the centre of the furnace and is removed from time to time by means of tilting trucks II for further treatment.

The sulphurous gases evolved during the roasting in the hearths flow along a 8 8 P th over the ore or the roasting material and upwards through the apertures ii to iinally escape through a conduit 12 to the separate plant for the recovery of sulphuric acid and for purification and concentration.

Owing to the invention it is possible to build the roasting chambers as low as possible because the rabble arms are interchangeable and mounted in the underside of the hearth plates so that they require almost no separate space in the roasting chambe The rabble arms can be re-' moved at any one time from the outer side from any of the hearth plates, the position of the rabbler teeth can be altered and the rabble arms reinserted. The furnace is thereby interrupted only for a very short time. The height of the roasting chambers depends merely on the height of the rabbler teeth which are adapted to the kind of ore to be treated and can be altered as required. With this object in view the stationary hearth plates are all arranged so that they can be adjusted in vertical direction in orderthat the roasting chambers can be adapted, when desired, to the height of the ore layer and of the rabblers which are moving the layer.

This advantage is obtained according to the invention only by the fact that the stirring arms are embedded in the under surface of the hearth plates and therefore do not require a separate space, wherefrom results a low height of the roasting chambers which could not hitherto be attained. By the low height of the roasting chambers a high speed of the roasting air admitted and of the discharge gases from roasting over the ores to be roasted is obtained, so that with lowest oxidation temperature an extremely eflective and very rapid roasting of the ores, that is a maximum output of the furnace, is obtained with lowest consumption of heat. I- claim:-

1. A roasting furnace for-roasting sulphurous ores, zinc blende, pyrites or for calcining any ores, comprising in combination a plurality of superposed roasting hearths formed by hearth plates alternately stationary and rotary and each having a plurality of radial grooves in their imder side, rabble arms me removably inserted in each furnace, downwardly projecting rabble teeth flxedatadistanceapartoneachof saidarms, a flange projecting from the circumference of each of said plates, columns arranged at distances apart around the periphery of said plates, brackets on said columns projecting under said flanges and directly supporting the outer edge of said stationary plates, rollers one on each of the brackets under the flanges of said rotary plates bearing against the under side of these flanges and adapted to support the outer edge of said rotary plates during their rotation, a rack on the periphery of the flanges of said rotary plates,

pinions meshing with each of said racks, and a driven shaft carrying said pinions and adapted to rotate said rotary plates through the intermediary of said pinions and said racks.

3.Awashingfurnaceasspecifledinclaim1, in which the radial grooves are of T-shape and 'the rabble arms have each a head of T-shaped cross-section corresponding to the shape of the radial grooves.

4. In a rotary furnaceas specified in claim 1 each of the rabble arms provided with a plurality of parallel longitudinal passages intercommunicating at one-end, a central double-walled hollow pipe carrying the rabble arms of the rotary hearth plates, the inner portion of said hollow pipe connected to one of the longitudinal passages in each of the rotary rabble arms and adapted to supply cooling air into said rabble arms, and the outer portion of said hollow pipe connected with another; passage of each of said rotary rabble arms and adapted to, lead of! the heated cooling air from said rabble arms, vertical air supply pipes connected with the inner portion of said hollow pipe and arranged around the periphery of the stationary hearth plates communicating with one of the passages in the rabble arms in these stationary plates and adapted to supply cooling air to the stationary rabble arms, and vertical discharge pipes one arranged adjacent each of said vertical air supply pipes communicating with another of ,the passages in the rabble arms in these stationary hearth plates and adapted to lead 01! the heated cooling air therefrom.

5.1harotaryfurnaceasspecifledinclaiml each of the rabble arms provided with a plurality of parallel longitudinal passages intercommunieating at one end, a central double-walled hollow pipe carrying the rabble arms of the rotary hearth plates, the inner portion of said hollow pipe connected to one of the longitudinal passages in each of the rotary rabble arms and adapted to supp y cooling air into said rabble arms, and the outer portion of said hollow pipe connected with another passage of each of i rotary rabble arms and adapted to lead 01! th heated cooling air from said rabble arms, Vertical air supply pipes connected with the inner portion of said hollow pipe and arranged around the periphery of the stationary hearth plates in the.

the rabble arms in these stationary hearth plates and adapted to lead oi the heated coolin: air therefrom, said rabble arms having a third passage adapted to supply preheated air between the superposed hearth plates.

' WIIJ-IELM MUELLER. 

